GB2522318A

GB2522318A - Prefixing for an adhesive application with temperature compensation

Info

Publication number: GB2522318A
Application number: GB1420630.4A
Authority: GB
Inventors: Marcus Lange
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2013-11-23
Filing date: 2014-11-20
Publication date: 2015-07-22
Also published as: GB201420822D0; DE102013019822A1; GB201420630D0

Abstract

A composite motor vehicle body can be formed from first and second body parts 9, 10 from respective first and second materials having different thermal coefficients of expansion by a method including prefixing body parts 9, 10 at one or more prefixing points 11, for example by welding, clinching and/or rivets, and connecting body parts 9, 10 at an adhesive joint (12, Figure 6) by means of adhesive. At least one body part 9, 10 has an area 14 surrounding prefixing points 11 so that at a compressive or tensile force area 14 demonstrates a smaller ratio of compressive or tensile force to linear change than outside area 14, for example by area 14 having a smaller thickness or a recess. Suitably, area 14 absorbs most of the deformation caused by thermal expansion and so provides a reliable joint. In an embodiment, first body part 9 may comprise steel, aluminium or other metal, and second body part 10 may comprise plastic.

Description

Prefixing for an adhesive application with temperature compensation

DESCRIPTION

The present invention concerns methods for manufacturing a motor vehicle in accordance with the preamble of claim I and a motor vehicle in accordance with the preamble of claim 12.

In motor vehicle engineering, bodies for motor vehicles are manufactured with a composite construction. The body is constructed and assembled from a plurality of body parts and the body parts consist of a material with a different thermal coefficient of expansion, for example a body with a composite construction having body parts made of steel and aluminium, or having body parts made of steel and plastic. A positive substance adhesive joint using * 20 adhesive is selected as the bonding method for connecting the body parts made from the material with a different thermal coefficient of expansion. In the 0*** first instance adhesive is applied to a glue surface of at least one body part and the body parts are then prefixed, for example, by means of rivets or welding, so that the body parts which are to be permanently joined to one another for large loads are already firmly aligned with each other geometrically on the adhesive joint. After this prefixing and/or the geometric alignment of the body parts with one another, the entire body with the number of body parts undergoes cathodic dip coating and then the cathodic dip coating is dried in a drying process in a drying oven at approximately 180 °C.

The adhesive used to join the body parts together is activated and/or cured during the heating process and/or during the drying process so that curing and activating of the adhesive to join the body parts together is only carried out after the cathodic dip coating process. The body parts used have a different thermal coefficient of expansion so that when the body is heated in the drying oven, various temperature-related linear expansions occur. As a result, these different linear expansions of the body parts made from the different materials lead to differences in linear expansion between the body parts made from the different material. As a result of these different linear expansions and the resulting differences in linear expansion between the body parts made from different materials, deformations, in particular, curvatures and plastic deformations, occur on body parts as a result of high compressive or tensile forces. As a result of these curvatures and plastic deformations, it is no longer possible to produce the adhesive joint reliably and in a distortion-free manner as the deformations occur between the glue surfaces of the body parts to be joined to one another, and during these deformations the adhesive was not completely or only partially cured and/or was only activated during heating in the drying oven. A distortion-free and reliable adhesive joint between the body parts made from the different materials with the different thermal coefficients of expansion cannot be produced therewith.

* 0 SO * S The object of the present invention is, therefore, to provide a method for 7 manufacturing a motor vehicle and a motor vehicle in which a body can be *55 * 20 reliably and securely produced with a composite construction where the adhesive is activated during drying after dip coating the adhesive joint between *:.; body parts.

This object is achieved with a method for manufacturing a motor vehicle with a body with a composite construction process having the following steps: providing at least one first body part made from a first material, providing at least one second body part made from a second material, wherein the first and second materials have different thermal coefficients of expansion, prefixing at the at least one first body part to the at least one second body part at at least one prefixing point, joining the at least one first body part with the at least one second body * part with at least one adhesive joint by means of adhesive, wherein the first and/or second body part is provided such that on the first and/or second body part in a surrounding area of the at least one prefixing point the first and/or second body part has, with a compressive or tensile force, a lower ratio of compressive or tensile force to (result from this) change in length than outside the surrounding area. Doors, flaps and bonnets are also considered as the body, wherein the doors, flaps and bonnets can preferably be swivelled so that body parts which are doors, flaps and bonnets are also covered by this application for industrial property protection.

A tensile stress or tensile force is also considered to be a negative compressive stress or compressive force. As a result of the smaller ratio of compressive or tensile force to changes of length resulting therefrom in the surrounding area than outside the surrounding area, compressive or tensile forces are essentially absorbed in the surrounding area as adjustment deformations so that as a consequence of the adjustment deformation essentially no and/or only very slight temperature-related compressive or tensile forces or compressive or tensile stresses occur outside the surrounding area. Thus, no or only slight compressive or tensile forces occur on the glue surfaces between the body parts by means of the adhesive and, therefore, fundamentally no deformations occur as a result. The adhesive joint between the first and the second body part can thereby be reliably produced during the :: drying.pmcess in the drying oven. The first and/or second body part, therefore, has a notional significantly smaller modulus of elasticity in the surrounding area than outside the surrounding area. In particular, the ratio of compressive or tensile force to change of length in the surrounding area is around 0.9, 0.7, 0.5, 0.4, 0.2, 0.1 or 0.01 times smaller than outside the surrounding area.

In an additional embodiment, the first and/or second body part is provided such that in the surrounding area the first and/or second body part has a smaller thickness than outside the surrounding area and/or at least one recess is provided in the surrounding area. The smaller ratio of compressive or tensile force to change of length can also, for example, be achieved by the fact that in the surrounding area the first and/or second body part has a smaller thickness of the wall and/or a material, e.g. rubber, having a very small modulus of elasticity, is used on the wall of the surrounding area, so that, therefore, by the same effective compressive or tensile force in the surrounding area a considerably larger change of length occurs than outside the surrounding area.

In a supplementary embodiment, the at least one recess is produced by means of machine culling on the at least a first and/or second body part and/or a surrounding area is formed by at least two cuts-outs and at least one bar. As a result of the cut-outs and the bar a very large change of length and/or adjustment deformation of the bar can be achieved on the bar with only small compressive or tensile forces so that predominantly the entire temperature-related difference in linear expansion between the first and second body part is absorbed by the bar. In so doing, the bar is preferably aligned fundamentally vertical to an axis of linear expansion.

In a supplementary variant, the adhesive joint between the first and/or second body part is produced, in particular exclusively, outside the at least one :.:: surrounding area. The adhesive joint is produced outside the surrounding area, because in the surrounding area itself, large adjustment deformations * occur so that no reliable adhesive joint can be produced between the first and :a the second body part at the surrounding area. S..

In a supplementary vanant, the at least one first body part is first prefixed to the at least one second body part at at least one prefixing point, then the at least one first and one second body parts undergo a, preferably cathodic, dip coating, then the at least one first and one second body parts are dried in a drying process and during the drying process the adhesive of the at least one adhesive joint is activated and/or cured.

In an additional embodiment, the at least one first and one second body parts are heated to an increased drying temperature, in particular between 70 °C and 300 °C, preferably between 120 °C and 220 °C, during the drying process.

Expediently, during heating for the drying process, different temperature-related linear expansions are realised on the at least one first body part and the at least one second body part because the first and second materials have a different thermal coefficient of expansion so that temperature-related differences in linear expansion occur between the at least one first body part and the at least one second body part and the differences in linear expansion are fundamentally absorbed as an adjustment deformation in the at least one surrounding area.

The overall deformation is fundamentally, i.e. at least by 60 %, 70 %, 80 %, 90 % or 95 %, absorbed by the surrounding area as an adjustment deformation.

In an additional embodiment fundamentally no deformation, in particular no curvatures and/or plastic deformations are realised on the at least one first body part and on the at least one second body part outside the at least one surrounding area during heating for the drying process, and/or fundamentally no compressive or tensile forces occur. Fundamentally no deformations occur outside the surrounding area, i.e. the deformations outside the surrounding area are less than 10 %, 5 % or 2 % of the adjustment deformation on the associated surrounding area.

In a supplementary variant the prefixing is realised by means of welding, clinching and/or rivets.

In an additional embodiment, the at least one first and the at least one second body part are attached to each other by means of prefixing at the at least one prefixing point and by means of joining to the body by means of at least one adhesive joint for the vehicle.

In a supplementary embodiment the at least one first body part made of metal, preferably steel or aluminium, and the at least one second body part made of plastic is provided, or the at least one first body part made from steel and the at least one second body part made from aluminium are provided.

Motor vehicle according to the invention, comprising a body with a composite construction method having at least one body part made from a first material and at least one second body part made from a second material, wherein the first and second materials have different thermal coefficients of expansion, a drive motor, e.g. a combustion engine and/or electric motor, the at least one first body part being joined to the at least one second body part at at least one prefixing point, the at least one first body part being connected to the at least one second body part by means of at least one adhesive joint by means of adhesive at at least one glue surface, wherein the motor vehicle is produced by means of one of the methods described in this application for industrial property protection and/or at a compressive/or tensile force the at least one first and/or the at least one second body part has a smaller ratio of compressive or tensile force to change of length in the respective surrounding area of at least one prefixing point than outside the surrounding area. The motor vehicle is usually not fundamentally subjected to any compressive or tensile force in the surrounding area during normal operation, i. e. does not fundamentally demonstrate any adjustment deformation, and the above description only serves to describe the arrangement and construction of the surrounding area for the manufacturing process.

Preferably the first and/or the second body part has a smaller thickness in the * * surrounding area than outside the surrounding area and/or at least one recess is provided in the surrounding area.

In an additional embodiment, a surrounding area is formed from at least two cut-outs and at least one bar. ** * * * * * .*

In a further variant, the respective one surrounding area is at a distance of less than 10 cm, 7 cm, 5 cm, 3 cm, 2 cm or 1 cm from the at least one associated prefixing point, and/or the adhesive joint is formed between the at least one first and the at least one second body part exclusively outside the surrounding area.

Embodiments of the invention are described in more detail below with reference to the attached drawings.

Fig. 1 shows a side view of a motor vehicle, Fig. 2 shows a longitudinal section of a first and a second body part after

prefixing from the prior art,

Fig. 3 shows a top view of a first and a second body part in a first S embodiment without deformation in a surrounding area of a prefixing point, Fig. 4 shows a top view of the first and second body part in accordance with fig. 3 with the deformation on the surrounding area of the prefixing point in a first direction parallel to an axis of linear expansion, Fig. 5 shows a top view of the first and second body part in accordance with fig. 3 with the deformation on the surrounding area of the : 15 prefixing point in a second direction parallel to an axis of linear * expansion, 5.....

Fig. 6 shows a top view of a first and second body part in a second * embodiment, 5* Fig. 7 shows a top view of a prefixing point of the first and second body part in accordance with fig. 6 and Fig. 8 shows a flow diagram of a method for manufacturing a motor vehicle.

A motor vehicle 1 shown in fig. I has a body 8 with a composite construction, i.e. the body 8 comprises first body parts 9 made from steel and second body parts 10 made from aluminium. A drive motor 2, in particular a combustion engine 3 and/or an electric motor 4, is used to propel motor vehicle 1. Vehicle seats 7 for carrying persons are available within a passenger compartment 6 enclosed by the body 8 and, in addition, the body 8 also encloses a luggage compartment S for carrying luggage.

A first and second body part 9, 10 from the prior art is shown in fig. 2. To produce the body 8 from a number of first and second body parts 9, 10, said parts are first coated with an adhesive, not shown, on a glue surface 13 and then a prefixing is created at a prefixing point 11, for example, by means of rivets or welding, so that the first and second body parts 9, 10 are aligned geometrically fixed and unchangeably with each other. Once the body made from body parts 9, 10 has been dip coated, a drying process takes place in a drying oven at 180 °C. Whilst the body 8 is heated in the drying oven to 180 °C, the first body parts 9, which are made of steel, realise a smaller temperature-related linear expansion than the second body parts 10 which are made of aluminium. This leads to compressive stress and/or compressive forces on the first body part 9 and tensile stress and/or tensile forces on the second body part 10. The compressive stress on the first body part 9 leads to a deformation of the first body part 9, in particular a curvature and a plastic deformation in * 15 accordance with the representation in fig. 2, so that the two glue surfaces 13 :.: ? on the first and second body part 9, 10 have a larger gap and, consequently, a distortion-free and reliable production of adhesive joint 12 on the glue surfaces 13 of the first and second body parts 9, lOis no longer assured.

Figs. 3 to 5 show a top view of the first and second body parts 9, 10 for a motor **..* vehicle I according to the invention and for a method according to the *.: invention for producing the motor vehicle 1. In so doing, the top view of only one prefixing point 11 is shown. A surrounding area 14 has a distance of less than 3 cm from the prefixing point 11 as a welded joint between the first and second body part 9, 10. On the surrounding area 14, two crescent-shaped cut-outs 16 are incorporated as recesses 15 so that a bar 17 is present between the two cut-outs 16. During the heating of the body 8, made from the large number of first and second body parts 9, 10, for the drying process after cathodic dip coating, the difference in linear expansion between the first and second body part 9, 10 can be fundamentally completely absorbed by the surrounding area 14, as bar 17, in relation to the two cut-outs 16 with an effective compressive force and/or compressive stress in the direction of an axis of linear expansion with an existing compressive force on bar 17, demonstrates a considerably greater change of length i. e. an adjustment deformation on bar 17 than outside the surrounding area 14, i.e. on the glued surfaces 13 which are not shown in figs. 3 to 5. In so doing, the first and second body part 9, 10 realise movements and/or changes of length fundamentally exclusively in the direction of the axis of linear expansion 26 as corresponding bars (not shown) are formed on the second body part 10 with which the first body part 9 is guided in relation to the second body part 10. With an existing compressive force, bar 17 therefore realises a considerably greater change of length in the direction of the axis of linear expansion 26 and/or an adjustment deformation than the first body part 9 outside the surrounding area 14. The differences in linear expansion between the first and second body part 9, 10 which occur during heating are, therefore, fundamentally exclusively absorbed by the first body part 9 in the surrounding area 14 so that as a result fundamentally no compressive forces or tensile forces occur outside the surrounding area 14 or, therefore, on the glue surfaces 13 with the adhesive * * 15 joint 12 between the first and second body part 9, 10 and no deformations, in particular curvatures or plastic deformations, occur as a result either. As a *..*.* * result, the two glue surfaces 13 of the first and second body part 9. 10 lie flush with each other without a gap so that the adhesive between the first and second body part 9, 10 allows a reliable and distortion-free production of the adhesive joint 12 during activation in the drying oven. *.** * t * **.

In fig. 3, the surrounding area 14 is shown prior to heating, i.e. there are no compressive forces or tensile forces on the first and/or second body part 9, 10.

In fig. 4, a downward tensile force and/or tensile stress, i.e. negative compressive stress, according to the arrow in fig. 4 affects the first body part 9 so that the bar 17 buckles downward in the direction of the arrow as a result and, therefore, the top cut-out 16 increases in size and the bottom cut-out 16 decreases in size. In fig. 5, the reverse is the case in relation to fig. 4, i.e. an upward compressive stress and/or compressive force affects the first body part 9 so that bar 17 buckles upward in the direction of the arrow as a result and, therefore, the top cut-out 16 decreases in size and the bottom cut-out 16 increases in size. The surrounding area 14 shown in figs. 3 to 5 is suitable for prefixing points 11 having only one axis of linear expansion 26, i.e. fundamentally compressive forces only occur in the direction of the axis of linear expansion 26.

A second embodiment of the first and second body parts 9, 10 is shown in figs. 6 and 7. The first and second body part 9, 10 are prefixed to one another by means of four prefixing points 11 so that two perpendicular axes of linear expansion 26 occur as a result. The first and second body part 9, 10 is thereby fundamentally plate-shaped and the two axes of linear expansion 26 are fundamentally aligned in parallel and inside a notional plane formed by the first and second body parts 9, 10. In orderthatthe surrounding area 14 can be easily deformed as an adjustment deformation for the different linear expansions in the two axes of linear expansion 26, the surrounding area 14 has two internal cut-outs 16 which confine an internal bar 17, as welt as two external cut-outs 16, which confine two bars 17 between the external cut-outs 16 and the two internal * * 15 cut-outs 16. As a result, the surrounding area 14 shown in fig. 7 can absorb adjustment deformations in both axes of linear expansion 26.

* *..*. * *

Fig. 8 shows a flow diagram for the production of the body 8 of motor vehicle 1. Firstly, a plurality of first and second body parts 18, 19 are provided, i.e. first body parts 9 in production step 18 and second body parts 10 in production *.** step 19, e.g. by means of forming through pressing and cut-outs. A layer of *.: adhesive is then applied to a respective glue surface 13 on each body part 9, 10, which are made from steel and aluminium, i. e. the adhesive is applied in production step 20, and then body parts 9, 10 are laid on top of each other and prefixed at prefixing points 11 in production step 21. As a result, body parts 9, are geometrically aligned with each other rigidly and immovably and can then undergo cathodic dip coating together in production step 22. After the dip coating, the prefixed body 8 is introduced into a drying oven and heated in production step 23 and, in so doing the dip coat, is dried. During the heating operating in the drying oven different temperature-related linear expansions occur between the first and second body parts 9, 10, and these different differences in linear expansion are absorbed fundamentally by an adjustment deformation 24 in the surrounding area 14 around the prefixing points 11. As a result, fundamentally no compressive or tensile forces occur outside surrounding area 14 on the first and second body parts 9, 10 and resulting deformations do not occur either so that the glue surfaces 13 lie flush on top of each other during heating in the drying oven as well. After the dip coating has been dried and the adhesive cured as a result of its activation in the drying oven, final painting 28 of the body 8 is carried out in a colour selected for the motor vehicle 1.

On the whole, considerable advantages are associated with the method according to the invention for the production of motor vehicle 1 and with the motor vehicle 1 according to the invention. The differences in linear expansion between the first and second body parts 9, 10 are fundamentally absorbed by the adjustment deformations in the surrounding area l4so that, as a result, no compressive or tensile forces occur on the first and second body part 9, 10 outside the surrounding area 14 or on glue surfaces 13 and, therefore, a distortion-free and reliable production of the adhesive joint 12 is possible.

* At least one embodiment was described wherein it should be noted that a large *:*. number of variants exist in this regard. It should also be taken into account that the embodiment or the embodiments are only examples and the intention is not, therefore, to restrict the scope of protection, the applicability and/or * . feasibility or the construction in any way. The above description imparts to the * .* person skilled in the art suitable instructions to realise at least one embodiment. It should be understood that various modifications can be made in the functioning and the arrangement of the components described in an exemplary embodiment without deviating from the scope of protection of the claims below or from the equivalents of the claims below.

REFERENCE LIST

I Motor vehicle 2 Drive motor 3 Combustion engine 4 Electric motor Luggage compartment 6 Passenger compartment 7 Vehicle seat 8 Body 9 First body part Second body part 11 Prefixing point : 15 12 Adhesive joint 13 Glue surface * **...

* 14 Surrounding area Recess 16 Cut-out 17 Bar 18 Provision of the first body part *:*.: 19 Provision of the second body part Application of adhesive to a glue surface 21 Laying on top of each other and prefixing the first and second body parts 22 Dip coating of the first and second body parts 23 Heating and drying of the first and second body parts 24 Adjustment deformation of the surrounding area Final paintwork 26 Axis of linear expansion

Claims

CLAIMS1. Method for producing a motor vehicle (1) having a body (8) with a composite construction by means of the following steps: -provision of at least one first body part (9) made from a first material, -provision of at least one second body part (10) made from a second material, wherein the first and second materials have a different thermal coefficient of expansion, -prefixing of the at least one first body part (9) to the at least one second body part (10) at at least one prefixing point (11), -joining the at least one first body part (9) with the at least one second body part (10) with at least one adhesive joint (12) by means of adhesive, *0-** * wherein ** * * * . * .* the first and/or the second body part (9, 10) is provided such that on the first and/or the second body part (9, 10) in a surrounding area (14) of the at least one prefixing point (11) at a compressive or tensile force, the first and/or the second body part (9, 10) in the surrounding area (14) demonstrates a smaller ratio of compressive or tensile force to change of length than outside the surrounding area (14).
2. Method according to claim 1, characterised in that the first and/or the second body part (9, 10) is provided such that in the surrounding area (14) the first and/or second body part (9, 10) has a smaller thickness than outside the surrounding area (14) and/or at least one recess (15) is provided in the surrounding area (14).
3. Method according to claim 2, characterised in that the at least one recess (15)is produced with cut-outs on the at least one first and/or second body part (9, 10) a nd/or a surrounding area (14) is formed from at least two cut-outs (16) and at least one bar (17).
4. Method according to one or more of the previous claims, characterised in that * *. 15 the adhesive joint (12) between the first and/or the second body part (9, 10) is produced, in particular exclusively, outside the at least one *..fl.* surrounding area (14). ** * * * * .*
5. Method according to one or more of the previous claims, * tee ::::; characterised in that firstly the at least one first body part (9) is prefixed to the at least one second body part (10) at at least one prefixing point (11), then the at least one first and second body part (9, 10) is subjected to a, preferably cathodic, dip coating, then the at least one first and second body part (9, 10) is dried in a drying process and during the drying process the adhesive of at least one adhesive joint (12) is activated and/or cured.
6. Method according to claim 5, characterised in that during the drying process the at least one first and second body part (9, 10) is heated to an increased drying temperature, in particular between 70°C and 300°C, preferably between 120°C and 220°C.
7. Method according to claim 5 or 6, characterised in that during the heating for the drying process on at least the one first body part (9) and the at least one second body part (10) different temperature-related linear expansions are realised because the first and second materials have different thermal coefficients of expansion * so that between the at least one first body part (9) and the at least one second body part (10) temperature-related differences in linear expansion occur and the differences in linear expansion are fundamentally absorbed as adjustment deformation on the at least :::::; one surrounding area (14).
8. Method according to claim 6 or 7, characterised in that during the heating for the drying process on the at least one first body part (9) and the at least one second body part (10) outside the at least one surrounding area (14) fundamentally no deformation, in particular curvature and/or plastic deformation, is realised and/or fundamentally compressive or tensile forces do not occur.
9. Method according to one or more of the previous claims, characterised in that the prefixing is realised by means of welding, clinching or rivets.
10. Method according to one or more of the previous claims, characterised in that the at least one first and the at least one second body part (9, 10) are joined by means of prefixing at the at least one prefixing point (11) and by means of joining by means of the at least one adhesive joint (12) to form the body (8) for the motor vehicle (1).* *. 15 * * S
11. Method according to one or more of the previous claims, *..* * S characterised in thatS S..

Sthe at least one first body part (9), is provided made from metal, in ::::; particular steel or aluminium, and the at least one second body part * (10) is provided made from plastic or the at least one first body part (9) is provided made from steel, and the at least one second body part (10)is provided made from aluminium.
12.Motor vehicle (1), comprising -a body (8) with a composite construction having at least one first body part (9) made from a first material and at least one second body part (10) made from a second material, wherein the first and second materials have different thermal coefficients of expansion, -a drive motor (2), e.g. a combustion engine and/or an electric motor (3, 4), -the at least one first body part (9) being connected to the at least one second body part (10) at the at least one prefixing point (11), -the at least one first body part (9) being connected to the at least one second body part (10) by means of at least one adhesive joint (12) by means of adhesive on at least one glue surface (13), wherein the motor vehicle (1) is produced by means of a method according to one or more of the previous claims and/or at a compressive or tensile force, the at least one first and/or the at least one second body part (9, 10) in a surrounding area (14) of the at least one prefixing point (11) in the surrounding area (14) demonstrates a smaller ratio of compressive or tensile force to change of length than outside the surrounding area (14). * *
13-Motor vehicle according to claim 12, characterised in that *. * * *: the first and/or second body part (9, 10) in the surrounding area (14) has a smaller thickness than outside the surrounding area (14) and/or at least one recess (15) is provided in the surrounding area (14).
14. Motor vehicle according to claim 12 or 13, characterised in that a surrounding area (14) is formed from at least two cut-outs (15) and at least one bar (17).
15. Motor vehicle according to one or more of claims 12 to 14, characterised in that the respective surrounding area (14) has a distance of less than lOcm,7cm,5cm,3cm,2cmorlcmfromtheatleastone associated prefixing point (11) a nd/or the adhesive joint (12) between the at least one first and second body part (9, 10) is formed exclusively outside the surrounding area (14). * *. * * . *0 * * * * ** 6 * . * * *6 **. *.e. * 0 ***. ** * * * 0 * S.